Beneficiation of phosphate ore containing carbonates



United States Patent 3,375,067 BENEFICIATION OF PHOSPHATE ORE CONTAININGCARBONATES Joseph F. Haseman, Lakeland, Fla., assignor, by mesne "icesuch processes, sulfuric acid and phosphoric acid are used in a knownmanner.

A primary object of the present invention is to provide a process forthe removal of carbonate and organic impurities in phosphate ore, whileat the same time lower- I I. 5 gig2figg Agricultural Company a cor ingthe acid insoluble fraction therein. further object N0 Drawing Filed N04, 19 4 S 0 ,74 is to provide a process for the beneficlatlon ofphosphate 5 Claims. (Cl. 23-165) rock containing carbonates and otherrmpuritles 1n the production of wet phosphoric acid or production ofsuper- 10 phosphate fertilizers dwhile arllloidingdthe eipielnsive stegsof dewatering and rying t e'pro uct. t er spec c ABSTRACT OF THEDISCLOSURE objects and advantages will appear as the specificationPhosphate ores high in carbonate minerals are calcined proceeds. tochange the carbonate minerals to oxides and cooled. The process isapplicable to phosphate ore which as- The ores are then attritioned asby scrubbing, grinding, says more than about 3 percent CO and the oremay shaking, etc. to form a dry dust body, and the dust contain asubstantial amount of other impurities. In separated as dry dust byscreening, air classification, etc. one embodiment of the process, theore is calcined in The phosphate ore remaining after separation from theconventional calcination equipment, such as, for example, dust isdigested with acid for the production of Wet a direct fired rotary kiln,fluid bed calciner, etc., or the process phosphoric acid, superphosphatefertilizer, etc. like. Calcination temperatures may be in the range ofBy removing the dust which contains the bulk of the 900 to 2500' F., andpreferably in the range of 1200 carbonate materials in dryform,.theacid-insoluble fracto 1700 F. Rapid heating and cooling of the feed istion is reduced and the acid requirements for phosphoric favorable tosubsequent beneficiation, but is not essential acid and fertilizerproduction are reduced. to the successful use of the process. After thecalcining of the ore, the ore is subjected to attrition for the formingof a dust content, such attrition being produced by ThiS in ntio latesto th o t scrubbing or grinding or shaking, etc. It is found that oreconta ir iing t za rl aonates, ari d r ii i ggrt i cul a l y i t hz icalcinsd material h Sub]e.ct?d to substapnal aglta' upgnading ofphosphate ores that are high in carbonate ytelds {dust Portlon contammgthe mam body 9 impurities, such as limestone or dolomite, to raise theoxlde mlpuntles a Such dust then be re.moved m BPL grade of the ore andto reduce the acid require a dedustrng operation. The dedustrngorseparation of the ments for wet phosphoric acid and superphosphate fer-9 m the Phosphate ore material may be accomtihzer Production v pllshedin a yanety of ways, as, for example, by screen- Many of the wormsphosphate deposits are relatively 3 mg, alr classification, and otherwell-known methodsfor high in Carbonate minerals, which are primarilyhalcite J separating dust from the body of particulate mater als. anddolomite. While calcination is effective to upgrade the In foregomgOperanon. I prefer to 9 the calclned BPL in ores high in carbonates andorganic impurities, Ore rtpldly P the ?oolln.g.tends to hberate and lthis does not reduce the high acid requirements necesi Wilde slze.t.helmpunlles and to cooperate Sary for wet phosphoric acid production orproduction 40 agitation 1n the attrition operation for producing the1mof superphosphate fertilizers. Calcination primarily punty'contammgdust changes the carbonate minerals to oxides, and partially ThephosPhate ore after Separatlon f.rom the dust may or wholly reduces theorganic and the hydrate content then be Subject? Standard Oreqressuigprocedmes for in the parent ore. To reduce acid consumption forphosthe removal. of slhcate? and.other mpuntle? Such Standphoric acidand fertilizer production, it is necessary to ard S61.) arajflon RInclude magnet: Separatlon reduce these oxides, which are mainly calciumand magsaparatlon m fiotatlm} nesium Oxides, and to remove them in sucha manner Specific examples illustrative ofthe process may be set so asnot to increase the acid insoluble portion. Such out as follows: oxidesmay be removed by the addition of water, boil- Example I ing the water,and decanting the impurities in the form Samples of pebble phosphate(-2+14 mesh) taken of slime suspended in water. However, this procedurefrom the Lake Hancock mine in Florida were treated by results in anactual increase in the acid insoluble fraction heating 300 grams of thevarious samples at 1700 F. for and also requires dewatering and dryingsteps which are one hour in a muffle furnace. The term coarse pebblehigh in cost. includes samples that are essentially -2+4 mesh. Fine Bythe terms acid consumption and high acid repebble is essentially 4+14mesh. The calcined samples quirements, reference is made to thecustomary processes were air cooled, agitated by hand shaking for 3minutes dealing with phosphate rock or ores in phosphoric acid in aone-quart Mason jar, and the dust removed by screenproduction and thepreparation of superphosphate. In ing. The results are shown in Table 1herebelow:

TABLE 1 Assay Before Calcination, Assay After Dedustlng, PercentRecovery Sam 18 Type of Percent Assay After Calcination, Percent PercentofPcrggilgd Num er Pebble BPL Acid CO4 BPL Acid CO1 MgO BPL Acid MgO Wt.BPL

Insol. Insol. Insol A Coarse 40.4 12.8 17.4 46.9 16.4 1.1 5.62 68.8 13.23.39 61.5 77.3 B do 49. 8 12. 9 6. 0 54. 4 11. 4 1. 0 4. 67 62. 2 9. 83. 23 74. 5 85. 0 G 67.9 8.4 3.5 72.9 8.4 0.6 73.6 8.0 89.3 90.2 D 51.69.2 9.8 65.9 8.8 0.7 1.78 67.7 8.8 1.69 90.2 92.5 61.7 8.3 5.9 67.5 10.20.4 1.02 68.4 10.2 0.97 90.3 91.5 61.5 10.6 3.5 66.4 13.7 0.7 0.45 66.513.0 0.40 92.2 92.3 57.7 9.0 10.1 62.9 10.0 1.6 66.0 9.3 91.2 93.3 61.97.9 7.0 68.5 8.0 0.8 69.9 8.0 96.9 91.7 60.6 7.3 6.0 66.7 10.8 0.8 4.0767.7 10.3 3. 34 94.1 95.4

The process was carried out as described in Example I except thatinstead of dedusting, the calcined ore was cooled and immersed in water,scrubbed with an agitator, and the fine liberated calcium and magnesiumoxides were then removed by decantation through a ISO-mesh screen. Theresults are shown in Table 2.

. 4 t those skilled in the art'without departing from the spirit of myinvention.

I claim:

1. In a process for treatment of phosphate ores containing carbonates toreduce acid requirements for ph0s phoric acid and fertilizer production,the steps of calcining the ores at a temperature in the range of 900 to2500 F., attritioning the calcined ore to form a dry body of dustimpurities, and separating said dust as dry dust from the phosphate ore.

2. The process of claim 1 in which said calcining step is carried on attemperatures in the range of 1200 to 1700 F.

3. In a process for the treatment .of phosphate ores containingcarbonates, the steps of calcining the ores at a temperature in therange of 900 to 2500 F., attrition- TABLE 2.BENEFICIATION OFHIGH-CARBONATE FLORIDA PEBBLE PHOSPHATE BY CALCINATION AND SLAKING EssayBefore Assay After Assay After Percent Recovery Calcination, PercentCalcinatiou, Percent Slaking, Percent of Calcined Sample Type 01 ProductNumber Pebble BPL Acid CO1 BPL Acid CaO BPL Acid CaO Wt. BPL

Insol. Insol. Insol.

While an increase in BPL was obtained, it was found that theacid-insoluble portion present after the calcination was actuallyincreased after the slaking operation. In comparison with the dedustingoperation described in Ex ample I, it was found that the dedustingprocedure described in Example I was eifective in decreasing theacidinsoluble fraction, while the water slaking procedure described inExample II increased the acid-insoluble fraction.

Example III The process may be carried out as described in Example Iexcept that after calcination, the ore is subjected to dry grinding andto air classification, the dust being sent to waste and the upgradeddust-free product being then subjected to further upgrading by standardore dressing procedures for the removal of silicates and otherimpurities. The upgraded dust-free product responds readily to magneticseparation and air flotation in an aqueous system as commonly used forthe removal of silicates and other impurities in standard ore dressingprocedures. The phosphate concentrate then obtained is treated withsulfuric acid for the production of phosphoric acid, or, alternatively,is treated with phosphoric acid for the production of superphosphate.

While in the foregoing specification I have set forth embodiments of theinvention in considerable detail for the purpose of illustrating theinvention, it will be understood that such detail or details may bevaried widely by ing the calcined ore to form a body of dry dustimpurities, separating said dust as dry dust from the phosphate ore, andsubjecting the ore to acid treatment for the recovery of phosphoricacid.

4. The process of claim 1 in which the calcined ore is rapidly cooledbefore the ore is attritioned.

5. In a process for the acid digestion of phosphate ores containingcarbonates to reduce the acid requirements for phosphoric acid andfertilizer production while decreasing the acid-insoluble fraction, thesteps of calcining the ores at a temperature in the range of 9002500 F.,cooling the ore, crushing the calcined ore to produce dry dust,screening the crushed material to remove the dust as dry dust from thephosphate ore, and thereafter subjecting the ore to digestion with acid.

References Cited UNITED STATES PATENTS 2,868,618 1/1959 Oberg et a123-165 X 3,113,838 12/1963 Perri et al. 23--165 3,192,014 6/1965 Leyshonet al 23165 3,235,330 2/1966 Lapple 23-165 FOREIGN PATENTS 47,961 1/1964 Poland.

OSCAR R, VERTIZ, Primary Examiner.

A. J. GREIF, Assistant Examiner.

